[Skip Fix]

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

[PAUL K]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

Tons of torque from the long and relatively small intake tract.... IMO

[PontiacJim1959]

Reading this post we have different conversations going all over the place, from 428 to Olds power boats.

Let's start with emissions. Thank you, California. Yep, that's where it began. 1961 an administrative organization called the Motor Vehicle Pollution Control Board (MVPCB) was created. Later changed to the State of California Air Resources Board in 1967.

In 1961 the board required all new motor vehicles sold in California to have crankcase emission control devices (namely to control engine blow-by gases) as factory installed equipment aimed at reducing hydrocarbons down from 1.25 pounds per car per day to 1.0 pounds. This changed in 1966 when unburned hydrocarbons had to be limited to 275 part per million (ppm) and the carbon monoxide to a 1.5% concentration by volume dropping the pollution levels to .046 pounds per day per car. The projected number that California was looking to see by 1970 was 0.20 pounds per vehicle per day.

Thus began the introduction of the PCV valve, the closed crankcase system, A.I.R. systems, open chamber heads, thermostats changed from 180 to 200 degrees, reduction of idle port holes/limited idle screw adjustments, retarded timing controls and the double acting vacuum advance can, the catalytic "after burner" (yes, 1968), and the gasoline vapor recovery systems. All thanks to California and mandatory on all cars/engine sold in California and this was all by 1968, and of course more was to come after 1968. In other states, some of these requirements were not required and thus a CA car will have the AIR system while one in New York would not, but still had the AIR heads. The better burning open chamber heads did away with the AIR system......but it did return at a later date along with those charcoal canisters if anyone recalls those.

The use of the Oldsmobile 403CI came about because it was the only comparable engine to the Pontiac 400CI that met California emissions standards. So California cars were fitted with the Olds engine in lieu of a Pontiac 400. The 403 was also an optional engine on the Catalina.

The Olds may have had smaller valves (2.07/1.62) and even flowed less than a Pontiac head, but the use of a longer duration and higher lift did wonders for the W30 option. The 1970 W30 455 was rated at 370HP @ 5200 RPM and 500TQ @ 3600. The cam had a 328 duration on Int/Ex, Lift was .475, and had an overlap of 108 degrees! So do you want to compare it to the 370HP RA IV or the 360HP 455? Oldsmobile had some hot set-ups to include the W31 350 with its 308 duration cam and .474" lift and 82 degree overlap cam. Same HP as the Pontiac 350HO, but my guess is it'll outrun the 350HO.

You can also look to an earlier time when the engine option in 1966 on the 442 could be had with the 400CI, tri power, ram air induction, close ratio 4-speed, and 4.33 gears and would have been the match to Pontiac's 389 XS tri power, ram air option.

I have never owned an Olds 442, but I would say they had a few engine options that may have put a hurting on a Pontiac GTO, or a Tempest/Lemans with the 350HO.

[Schurkey]

Originally Posted by PontiacJim1959

the catalytic "after burner" (yes, 1968)

No catalyst before model-year 1975. I think you mean "Thermal Reactors".

Essentially after-burning exhaust manifolds fed with fresh air from the AIR pump or the Pulse Air system. The added oxygen allowed the overly-rich mixture to continue to oxidize.

[PontiacJim1959]

Originally Posted by Schurkey

No catalyst before model-year 1975. I think you mean "Thermal Reactors".

Essentially after-burning exhaust manifolds fed with fresh air from the AIR pump or the Pulse Air system. The added oxygen allowed the overly-rich mixture to continue to oxidize.

Ah, you are an automotive engineer - I say that with no disrespect. So here is the complete info I got this from as the word "catalytic" caught my attention. The topic is headed AFTERBURNERS. My book source is published 1968 and specific to automotive emissions systems of all the US manufacturers and the diagnosing, troubleshooting, calibrating, and repair of the systems.

"The two types of afterburners that have received extensive development work to date are the catalytic and the flame type. The catalytic afterburner is designed to consume the discharged hydrocarbons by means of heat developed through a chemical reaction. The units may be positioned at the muffler or in the exhaust manifold. Chemically coated pellets are arranged so that the flow of hot gases activates them; the pellets then promote oxidization of the unburned hydrocarbons. The flow of gases also must agitate the pellets in order to reduce carbon build up in the catalytic bed. Temperatures required to maintain this chemical reaction range from 400 degrees to 1,300 degrees."

So, as you can read, it is exhaust heat activating chemically treated pellets - not air injection.

However, the same section also describes another system - a flame-type afterburner:

"The flame-type afterburner consumes unburned hydrocarbons by means of an open flame. This system requires the adjustment of the carburetor and distributor to produce, as fuel for the flame, a controlled concentration of the unburned material in the exhaust stream. The exhaust must be kept rich enough or the afterburner will "flame out." If the exhaust is too rich, the unit will burn out from excess heat. Also, the extra gasoline needed to keep the burner going exacts a 3-7 percent fuel consumption penalty."

So both devices/concepts use heat and I fail to see in the description of either anything about injecting air?

The type system you describe has nothing to do with a catalytic system as described above, but the Air Injection Reaction System (A.I.R) is what you reference. For your recollection, and the others who may have never even seen one of these nifty units, I will clarify and describe some basic operations of the system.

"The AIR system consists of an air pump (belt driven) that constantly forces air into each exhaust port immediately after the exhaust valve. Since the exhaust gases at this point are above kindling temperature and have an excess of hydrocarbons, the infusion of oxygen starts the mixture burning and so consumes the hydrocarbons that normally would be expelled into the atmosphere.
The AIR system pump draws air from the air cleaner/air filter canister and forces it through two outlet hoses (one for each side on a V8 engine) through a check valve and into an air manifold, where it is delivered to each cylinder through stainless steel nozzles that project into the exhaust port."

I won't get into the fine points as the system has many features in the event of backfires, pressure changes, high speed pumping, and the like.

[Formulajones]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

Hmmm, all the jet boats and mini off shore racers I ever saw or rode in were mainly BBC's with a few exceptions. My buddies jet boat ran a 460 ford with a tunnel ram. I don't ever recall seeing one with an Olds.

[geeteeohguy]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

There were a lot of Olds powered jet boats in the early 80's were I was in CA as well. As a mechanic at a general shop (worked on every make) from the late 70's through the mid '90's, I saw a lot of the old large-bore V8's. Of them all, the Oldsmobile 455 was the most durable, and would put up with the most abuse/neglect. So running an Olds in a boat at high load most of the time would make sense, as there would be less down time. BBC's had valve issues, Cadillacs liked to toss rods, and Pontiacs liked to spin bearings. The old FE Fords were durable, but by then, the 427's were a lot of money. Used Olds 455's were cheap and all over the place...and they held up.

[MarkS57]

Originally Posted by geeteeohguy

There were a lot of Olds powered jet boats in the early 80's

I really wanted to get into jet boats in the mid 70's and likewise, those blue 455 Olds jets seemed to be everywhere.

My friend was really into the W30 455's in those days and had some trouble keeping the rod bearings from spinning.

[455Grandville]

Originally Posted by MarkS57

I really wanted to get into jet boats in the mid 70's and likewise, those blue 455 Olds jets seemed to be everywhere.

My friend was really into the W30 455's in those days and had some trouble keeping the rod bearings from spinning.

Olds V8s are pretty durable but had a flimsy weak bottom end if you plan on pushing them unless you use the diesel block or girdled it.

[John Milner]

I'm kind of partial to 428's. They just build tons of torque and love to rev. I wish Pontiac could have made a Ram Air IV 428 in '69. That really would have been a great engine for a GTO or Firebird.

[Douglas Willinger]

Thread on my 434 Ram Air Iv build:

http://psp.aquacomp.net/topic.asp?TO...TOPIC_ID=13682

[72LuxuryLeMansLa.]

Originally Posted by Douglas Willinger

Thread on my 434 Ram Air Iv build:

http://psp.aquacomp.net/topic.asp?TO...TOPIC_ID=13682

Doug,
The link brings me to the log on page.... Guidance to find the thread?

[Douglas Willinger]

Originally Posted by 72LuxuryLeMansLa.

Doug,
The link brings me to the log on page.... Guidance to find the thread?

Go to " Restoration & Performance Forum"

page 3

1970 Ram Air III/IV 434 Build
1 2 3 4

start of thread http://psp.aquacomp.net/topic.asp?TOPIC_ID=13682

The most recent post is July 26, 2018

[goatwgn]

How about the 455 block, fitted with a 428/421 crank, and correct pin height pistons?

[bobzdar]

Originally Posted by goatwgn

How about the 455 block, fitted with a 428/421 crank, and correct pin height pistons?

455 block with 428 crank is just an .030 over 428 (or .060 over 421) for 434 inches.

[PontiacJim1959]

Originally Posted by bobzdar

455 block with 428 crank is just an .030 over 428 (or .060 over 421) for 434 inches.

GM Corporate would have never allowed it as it would have upstaged the Camaro SS - which did get the 427CI.

Baldwin-Motion Performance offered the SS-427 Camaro and was "guaranteed to run 120MPH in 11.50 seconds." $3,595.00 and its all yours.

[goatwgn]

Originally Posted by bobzdar

455 block with 428 crank is just an .030 over 428 (or .060 over 421) for 434 inches.

Yes. but it does give someone the option of using a 4 inch stroke in a more readily available block. A lot of people have done this. (Should have clarified it in my original post) Lots more 455 blocks than 428s. Plus, you get a few more cubes with overbores up to .060.

[slowbird]

Originally Posted by Skip Fix

So I'll throw a slightly related but tangential question -why did most of the jet boats in the 70s early 80s use Olds 455s vs Chevy 454, Pontiac , Buick 455s?

Because no one would care if the boats sank